Comprehensive network monitoring at broadcast satellite sites located outside of the broadcast service area

ABSTRACT

A system and method for monitoring the quality of signals transmitted to a remote service area that is located outside of the broadcast area of a main broadcast site. The present invention converts and combines the signals that are to be broadcast from the main broadcast site to a satellite for redistribution to the remote service areas. The converted and combined signals are looped back to a network monitoring operations located at the main broadcast site before being transmitted to the satellite. In another embodiment, the remote broadcast sites send signal strength measurements to the network monitoring operations to provide an indication of satellite transmission problems not related to the quality of the signal being broadcast from the main broadcast site.

RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 10/291,165 filed on Nov. 8, 2002, entitled “ComprehensiveNetwork Monitoring At Broadcast Satellite Sites Located Outside Of TheBroadcast Service Area”.

TECHNICAL FIELD

The present invention relates generally to network monitoring of abroadcast signal transmission and more particularly to comprehensivenetwork monitoring of a broadcast signal transmission at broadcast siteslocated outside of a broadcast service area.

BACKGROUND OF THE INVENTION

It is essential that comprehensive network monitoring of the broadcastsignal be maintained to provide early detection, troubleshooting andproblem resolution. Typically there is an undiminished capability formonitoring a broadcast signal because the information and signals arereadily available to the network operations functions as theseoperations are within the broadcast area. A single, central networkmonitoring function is provided in the service area.

When the broadcast system has one or more service areas that havelocations that do not include the broadcast site, the channels beingbroadcast cannot be directly received at the service area. A possiblesolution is to deliver all of the broadcast signals back to the networkmonitoring function. However, this solution introduces significant costas the broadcast signals typically have very high bandwidth. Further,there is uncertainty in the quality of the monitoring because thetransmission path returning the broadcast signals to the networkmonitoring function may themselves introduce degradations and outagesthat do not actually occur in the broadcast itself.

Another possible solution is to create a distributed network monitoringfunction. Facilities could be provided in each service area. However,the facilities must be staffed twenty-four hours a day in order toperform the network monitoring functions. This is a huge cost burden.Furthermore, the success rate in troubleshooting and resolving problemswould most likely be lower due to the complexity of such a distributedorganization.

SUMMARY OF THE INVENTION

The present invention is a method of network monitoring of signalswithin the broadcast site that avoids the problems associated with theprior art. According to the present invention, the broadcast signalsthat are being transmitted to service areas outside of the broadcastsite are looped back into the network monitoring function immediatelybefore being broadcast outside of the site. The use of information andsignals are readily available to network operations functions within thebroadcast site and undiminished capability for monitoring of a broadcastsignal is maintained.

The present invention provides simplicity in that the same programcontent and management control signals (e.g., program guide signals,conditional access) are integrated into the service broadcasts and areused by the monitoring receivers to access desired channels. To monitoragainst problems in the transmission from the broadcast site to theservice area, a transmission monitoring system at the service areaprovides signal strength readings to the network monitoring system usinga low bandwidth return signal.

It is an object of the present invention to provide comprehensivenetwork monitoring functions for broadcast sites located outside of abroadcast area. It is another object of the present invention to performnetwork monitoring functions for the broadcast sites, or service areas,located outside of the broadcast area using a network monitoringfunction within the broadcast site.

Other objects and advantages of the present invention will becomeapparent upon reading the following detailed description and appendedclaims, and upon reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this invention, reference shouldnow be had to the embodiments illustrated in greater detail in theaccompanying drawings and described below by way of examples of theinvention. In the drawings:

FIG. 1 is an example of a spot beam satellite network utilizing thenetwork monitoring method of the present invention;

FIG. 2 is a block diagram of the network monitoring function of thepresent invention; and

FIG. 3 is a flow chart of the method of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 is an example of a spot beam satellite network system 10. Asatellite 12 services a plurality of service areas 14. A networkmonitoring center 16 broadcasts signals to the satellite 12. Thesatellite 12 redistributes the signals to the plurality of service areas14 by way of spot beams where the signals for the specific area arereceived by the intended recipients, i.e. television signals for areasubscribers.

The remote service areas are outside of the direct broadcast range ofthe centralized network monitoring center 16, making it impossible forthe network monitoring center 16 to receive the signals being broadcastto the remote service areas 14. According to the present invention, themonitoring function 20 for the remote sites is done at the broadcastsite 16 when the signal exits the network monitoring center. Theverification of the transmission delivery to the service area is done atthe remote site.

Referring now to FIG. 2 there is shown a block diagram of the networkmonitoring function 20 of the present invention. The network monitoringcenter 16 broadcasts a signal through an RF multiplexer (MUX) output 22that feeds an uplink antenna. Network monitoring of a high qualityoutput signal in the uplink can validate the content (program contentand management control signals) of the transmission in the spot beamdownlink unless there is a problem with the satellite transponder,satellite pointing or the uplink antenna is mispointed. These potentialproblems are addressed by the present invention later herein.

The uplink RF signals are downconverted by a signal converter andoptionally combined in a signal combiner 24, an L-band signal converteris shown in FIG. 2 for example purposes. One skilled in the art iscapable of substituting like components to accomplish results similar tothose of the present invention. The RF signals are downconverted to thefrequencies they will occupy in a customer's receiver (not shown)through the spot beam. In one embodiment of the present invention, thedownconverted signals are combined into groups that simulate the signalsa customer receiver will see in the spot beams. The RF signals arelooped back to a signal router 28 to the network monitoring operations30 where they are monitored for signal quality and content and anynecessary adjustments can be made.

When the quality of the outgoing signal is high, the signal that isreceived by the remote site will also be high quality, unless there is aproblem with the satellite transponder, satellite pointing or an uplinkproblem. As a check for transponder, pointing or uplink problems, theremote areas 14 have a signal strength meter 32 to measure the strengthof the signal received from the broadcast center 16. The signal strengthmeasurements 34 are transmitted back to the network monitoringoperations 30 where the system can guard against a satellitetransponder, pointing or uplink problem. The network monitoringoperations 30 has the capability to generate an alert should the signalstrength from a remote site degrade. An operator may also be able tobring back and monitor the program content and management controlsignals from any single channel in a spot beam downlink as a back-upcheck.

In broadcast video signals, a program guide is used to tune receiversfeeding monitors in the network monitoring operations 30. Typically, acomplete broadcast signal includes video, audio, data services, programguide and conditional access signals. The signals are broadcast in spotbeams. The prior art has the limited capability of monitoring only oneof the downlink beams and would require an additional network monitor atthe remote site for monitoring capability.

In order to permit use of the program guide to tune receivers feedingmonitors in network monitoring operations, the present inventiondownconverts the uplink RF signals to the L-band frequencies they willoccupy in a customer's receiver in the spot beam. The downconvertedsignals may be combined into groups that simulate all of the signalsthat subscriber receivers will see in the spot beams.

In another embodiment of the present invention, non-conflicting spotbeams may be combined into a superbeam to reduce the number of groupsgenerated in the combiner 26. The superbeam signal can be distributed asneeded to monitoring locations within the broadcast site.

The present invention includes the capability to measure the spot beamtransponder carrier strength and CONUS transponder carrier strength atthe remote area 14. A central computer at the broadcast site 16 monitorssignal strength measurements from all of the remote areas 14. Amonitoring program is used to continuously analyze the signal strengthmeasurements and raise an alarm upon loss of a signal or degradation ofthe transponder signal. The system also includes the capability to avoidfalse alarms due to rain fade. This is facilitated by the comparison ofthe spot beam transponder signal strength to the signal strength takenfrom another transponder of a satellite in the same orbital location.Either a spot beam or Conus transponder may be used for this comparison.A Conus transponder is preferred because of its ready availability atall ground or remote locations. The signal strength measurements may belogged in a database to support long term trend analysis of transponderperformance.

The method 100 of the present invention is described with reference toFIG. 3. A broadcast site broadcasts 102 signals to a satellite, wherethe signals are sent via spot beams to at least one remote service areaoutside of the broadcast site's range. The signals to be broadcast tothe satellite are first converted 104 into the frequencies they willoccupy in a customer's receiver in the spot beam. The converted signalsmay optionally be combined 106 into groups that simulate the signalsthat the customer will see in the spot beams. Any non-conflicting spotbeams may be combined into super beams to reduce the number of signalgroups.

The downconverted and combined signal is immediately looped back androuted 108 to a network monitoring operations at the broadcast sitewhere it is monitored 110 for signal quality, program content andmanagement control signals.

For further signal monitoring, a signal strength meter located at the atleast one remote site is sending 112 a signal strength measurement tothe network monitoring operations at the broadcast site. The signalstrength measurement allows the network monitoring operations todetermine 114 if there is a problem with the satellite transponder,pointing or uplink.

The monitoring program may continuously analyze the readings and raisean alarm 116 upon loss, or degradation, of a transponder signal. Theprogram also should have the capability to avoid false alarms due torain fade. In yet another optional step, the signal strengthmeasurements are logged 118 into a database to support long-term trendanalysis of spot beam transponder performance.

The invention covers all alternatives, modifications, and equivalents,as may be included within the spirit and scope of the appended claims.

1. A system for monitoring signal quality of signals to be broadcast toa satellite and broadcast in spot beams to a service area outside of abroadcast area comprising: a broadcast site within a predefinedbroadcast area, the broadcast site transmits the signals to thesatellite and the satellite transmits the signals to the service areaforeign to the broadcast; a network monitoring operations located at thebroadcast site for monitoring signal quality of the signals before thesignals are transmitted to a satellite; at least one remote site in theservice area that receives the signals broadcast by the satellite; asignal strength meter at said at least one remote site for measuring astrength of signals to detect problems with the satellite transmissionto the foreign service area; and means for collecting and monitoring thesignal strength measurements at the network monitoring operations;wherein the satellite transmits spot beams and the broadcast sitefurther comprises: a radio frequency (RF) multiplexer coupled to anunlink antenna transmitting the signals to the satellite; a signalconverter, coupled to the RF multiplexer to downconvert the signals tofrequencies bands upon which the signals are received by customerreceivers at the remote site; a combiner, coupled to the signalconverter, for combining the downconverted signals into groups tosimulate the signals received by the customer receivers in the spotbeams, further comprising a signal router disposed between the combinerand the network monitoring operations.
 2. The system as claimed in claim1 wherein the means for collecting and monitoring the signal strengthmeasurements further comprises: software for analyzing the signalstrength measurements; and means for raising an alarm upon loss ordegradation of the signal.
 3. The system as claimed in claim 2 whereinthe means for raising an alarm further comprises means for avoidingalarms for signal degradation that is a result of rain fade.
 4. Thesystem as claimed in claim 1 further comprising a database for storingsignal strength measurements from the at least one remote site therebyproviding a history of satellite transponder performance.
 5. The systemas claimed in claim 4 wherein the database further comprises using datastored in the database to support long term trend analysis of thesatellite transponder.
 6. The system as claimed in claim 1 wherein thesignal strength meter measures the signal strength of a CONUStransponder carrier signals.
 7. A method for monitoring a quality ofsignals broadcast to remote broadcast service areas located outside of amain broadcast area, the remote broadcast service areas having signalstrength meters, the main broadcast area having a broadcast site havinga network monitoring operations, said method comprising the steps of:multiplexing, at the broadcast site, the signals to provide the signalsto an uplink antenna for transmission to a satellite and to provide thesignals to a converter; converting, at the broadcast site, signalsprovided to the converter into frequencies upon which the signalsreceived by customer receivers in the remote broadcast service areas;looping, at the broadcast site, the converted signals provided to theconverter to the network monitoring operations; monitoring a quality ofthe looped signals at the network monitoring operations to determine ifmodifications to the signal quality are necessary; making necessarymodifications to the broadcast site to improve the signal quality;broadcasting a high quality signal to the satellite for spot beamtransmission to the remote broadcast service areas after completing thestep of making necessary modifications to improve the signal quality;measuring signal strength at the remote broadcast area; sending signalstrength measurements from the remote broadcast service areas to thenetwork monitoring operations; and determining the existence of asatellite transmission problem from the signal strength measurementsreceived at the network monitoring operations.
 8. The method as claimedin claim 7 further comprising the step of logging signal strengthmeasurements into a database at the network monitoring operations. 9.The method as claimed in claim 7 further comprising the step of raisingan alarm indicating degradation or loss of the signals based on thesignal strength measurements.
 10. The method as claimed in claim 9further comprising the steps of: determining signal degradation that isa result of rain fade; preventing the step of raising an alarm forsignal degradation that is a result of rain fade.